1. Field of the Invention
The present invention is concerned with new polymers and anti-reflective compositions for use in the manufacture of microelectronic devices. These compositions include a polyamic acid and are developable in aqueous photoresist developers.
2. Description of the Prior Art
Integrated circuit manufacturers are consistently seeking to maximize substrate wafer sizes and minimize device feature dimensions in order to improve yield, reduce unit case, and increase on-chip computing power. Device feature sizes on silicon or other chips are now submicron in size with the advent of advanced deep ultraviolet (DUV) microlithographic processes.
However, a frequent problem encountered by photoresists during the manufacture of semiconductor devices is that activating radiation is reflected back into the photoresist by the substrate on which it is supported. Such reflectivity tends to cause blurred patterns which degrade the resolution of the photoresist. Degradation of the image in the processed photoresist is particularly problematic when the substrate is non-planar and/or highly reflective. One approach to address this problem is the use of an anti-reflective coating applied to the substrate beneath the photoresist layer. While anti-reflective coatings are effective at preventing or minimizing reflection, their use requires an additional break-through step in the process in order to remove the coatings. This necessarily results in an increased process cost.
One solution to this problem has been the use of wet developable anti-reflective coatings. These types of coating can be removed along with the exposed areas of the photoresist material. That is, after the photoresist layer is exposed to light through a patterned mask, the exposed areas of the photoresist are wet developable and are subsequently removed with an aqueous developer to leave behind the desired trench and hole pattern. Wet developable anti-reflective coatings are removed during this developing step, thus eliminating the need for an additional removal step. Unfortunately, wet developable anti-reflective coatings have not seen widespread use due to the fact that they must also exhibit good spin bowl compatibility and superior optical properties to be useful as an anti-reflective coating. Thus, there is a need for anti-reflective coating compositions which are removed by conventional photoresist developers while simultaneously exhibiting good coating and optical properties.